1. Field of the Invention
The present invention pertains to apparatus for cutting metallic members. Specifically, the present invention pertains to broach apparatus suitable for cutting flat surface on a metallic member, specifically suitable for cutting a flat surface for engagement by hardness testing apparatus to determine the hardness of the metallic member.
2. Brief Description of the Prior Art
In the production and treatment of metallic goods, it is frequently desired to determine certain characteristics of the goods such as hardness. The hardness of such metallic goods can be measured by determining resistance to penetration. Several scales or standards of reference for hardness of materials have been developed over the years. Two of the most common scales or tests are the Rockwell hardness test and the Brinell hardness test.
In most hardness tests, a testing machine is provided capable of forcing a penetrating device against the material to be tested. Generally, in automatic readout testing, the material is first clamped against the testing machine with a force in excess of the loads to be applied during the test. During clamping, the penetrating device is recessed and out of contact with the material. Clamping eliminates distortion or movement of material prior to the test.
After the material is properly clamped, a preliminary or set load or force is applied to the penetrating device. Then a full load or force is applied to the penetrating device. The difference in penetration between the set load and the full load is measured by various means and correlated with standard scales to determine the hardness of the material.
In such hardness tests, it is extremely important that the surface of the material being tested be perfectly perpendicular to the load or force being applied through the penetrating device. This is no great problem with flat parts of specimens. However, on curved or rounded parts, such as pipe or other cylindrical members, this creats a problem. To assure that a flat surface is provided for testing, it is often necessary to cut a small flat surface on the surface of the pipe. This may be accomplished with a broach device or in other manners. However, if the flat surface is cut on the test specimen prior to placing in the test apparatus, it is often difficult to clamp the test specimen in place with the flat surface cut thereon being accurately placed and perpendicular to the position with respect to the penetrating force applied by the hardness tester. If the flat surface is not perpendicular to the testing force, the force vectors created by such a misalignment will result in inaccurate test measurements.
Furthermore, the cutting of flat surfaces on rounded members, such as pipe, during production results in substantial time delay of the production facilities. A flat surface must be accurately cut on the pipe and then the pipe accurately positioned in the testing device. Prior art methods and apparatus for performing these functions leave something to be desired in accuracy and results in substantial production line slow down or delay.